Deep mycoses

Deep mycoses. Fungal infection

1. INTRODUCTION Mycoses refers to infection by fungal agents. Fungi are eukaryotes with cell wall that grow as multi cellular filaments (molds) OR individual cells alone or in chains (yeast). Molds consist of thread like filaments called Hyphae.

2. INTRODUCTION Hyphae produce round cells , called Conidia, that easily become airborne, disseminating the fungus.

3. INTRODUCTION Many pathogenic fungi are dimorphic , forming hyphae at ambient temperatures but yeasts at body temperature ( e.g.Blastomyces , Histoplasma etc.). Mycoses are of Four major types – Superficial and coetaneous mycoses . Subcutaneous mycoses. Endemic mycoses. Opportunistic mycoses.

4. INTRODUCTION Deep mycosis includes – subcutaneous mycoses, endemic mycosis (caused by Dimorphic fungi) and Life threatening systemic illness in Opportunistic mycoses ,seen in Immuno compromised or prosthetized individuals.

5. METHODS OF SPECIMEN COLLECTION FOR DIAGNOSING MYCOSES The diagnosis of mycotic infection is contingent upon the proper selection, collection and transport of the appropriate clinical sample. Specimen volume must be adequate to perform all the tests. In case of inadequate sample at least two swabs to be taken for microscopy and culture. If material is inadequate , it can be collected with sterile swab stick moistened with NS.

6. CONTD… Skin scraping and hair should be transported in dry container or envelop. It is essential for specimens to be collected aseptically from the deeper part of the wound or else superficial contaminating fungi or bacteria will overgrow and suppress pathogenic fungi. Rapid transport of specimens in less than two hours ensures optimum recovery of fungi.

7. CONTD… Scanty material/ dry swab ,not acceptable. The ‘saline for injection’ solution which may contain anti microbial substance should be avoided while collecting biopsy tissue for HPE or grains from sinus tract. Tissue specimen to be sent in saline and not in formal saline , for culture.

8. TRANSPORT OF SPECIMENS Specimen must be transported and processed within two hours of collection preferably. To minimize the overgrowth of commensals (In case of specimen taken from nose, oral mucosa, nail etc.) Penicillin (20U/ml), Streptomycin (1,00,000 mcg/ ml) or Chloramphenicol (0.2gm/ ml) may be added to the specimen. In case of delay specimen can be stored under refrigeration at 4 degree C. but not more than 24 hours.

9. CONTD… Blood and CSF are stored at 30 - 37 degree C . Dermatological specimens at 15- 30 degree C. Specimen like subungual debris, hair, skin scraping can be directly inoculated on to the appropriate media immediately after collection for the optimum recovery of the fungi.

10. SUBCUTANEOUS MYCOSES MYCETOMA - etiologic agent may be bacterial or fungi.  Discussion here will be restricted to fungal mycetoma or eumycetoma . CHROMOBLASTOMYCOSIS PHAEOHYPHOMYCOSIS SPOROTRICHOSIS LOBOMYCOSIS RHINOSPORIDIOSIS

11. MYCETOMA Mycetoma - clincal syndrome of localized, indolent, deforming, swollen lesions and sinuses, involving cutaneous and subcutaneous tissues, fascia, and bone; usually occurring on the foot or hand) - etiologic agent may be bacteria or fungi. Mycotic mycetoma - usually more common in men (3:1 to 5:1) than in women. Usually results from trauma or puncture wounds to feet, legs, arms and hands (usually on the feet).

12. MYCETOMA Starts out as tumor-like to subcutaneous swelling. Ruptures near the surface; infects deeper tissues including subcutaneous tissues and ligaments (tendons, muscles and bone are usually spared). Small particles or grains leak out of the lesions -  these represent the yellowish microcolonies .

13. MYCETOMA Lesions of mycetoma seldom heal spontaneously. Disease is chronic may continue for 40-50 years. Ketoconazole appears to be ineffective in clinical trials. Intravenous miconazole (9 mg per Kg of body weight sometimes higher doses) shows promise. Surgery and removal of tumor ( if small it is encapsulate, if larger amputation my be required). Combining miconazole and surgery may prove useful in effectively treating the disease.

14. MYCETOMA

15. MYCETOMA

16. MYCETOMA Eumycotic mycetoma granules,pink coloured in PAS stain

17. CHROMOBLASTOMYCOSIS Disease is one of hyperplasia, characterized by the formation of verrucoid (rough), warty, cutaneous nodules, which may be raised 1-3 cm above the skin surface.  The roughened, irregular, pedunculated vegetations often resembles the florets of cauliflower. This disease is caused by Fonsecaea pedrosoi and Phialophora verrucosa (identical to Cadophora americana which causes bluing of lumber), both of which are dematiaceous fungi (darkly pigmented). occurs rarely in animals (such as, horses, cats, dogs, and frogs). soil-inhabiting fungi

18. CHROMOBLASTOMYCOSIS Susceptibility enhanced by going barefoot or wearing sandals. Found almost exclusively in laborers. Enters hand or feet after trauma. Found primarily in the tropics or subtropics. Dull red or violet color on skin may resemble a ringworm lesion. Develops into a verrucous lesion. Pruritus (itchiness) and papules may develop.

19. CHROMOBLASTOMYCOSIS Fungus gets under the skin (produces bumps). Bumps may block lymphatic system and cause elephantiasis. Sometimes bacterial infection may enter and cause a secondary infection. Rarely this fungus spreads to other areas of the subcutaneous tissue. Potentially may spread to brain (life-threatening in that case)

20. CHROMOBLASTOMYCOSIS Identification Biopsy tissue - look at the skin for fungus. Hematoxylin stain - look for fungal cells scattered among skin cells. Attempt to culture fungus from biopsy tissue must always take place to identify the etiological or causal agent . Colonies of fungi are dark or blackish. Two species implicated in this mycosis - each may produce several spore types Fonsecaea pedrosoi - Cladosporium type and Rhinocladiella type of conidiation Phialalophora verrucosa - Phialophora type (flowers in the vase conidiation ) Fungi found growing on plant debris, wood, soil.

21. CHROMOBLASTOMYCOSIS Treatment usually not fatal or necessarily painful unsightly disease no really good cure thiabendazole - shows promise (given orally and on skin mixed with dimethyl sulfoxide [DMSO] - to deliver drug) - experimental drug surgical excision, electrodesiccation , or cryosurgery are useful in early stages of disease application of heat to infect site has been reported to effect a cure of the disease after six months of treatment (using pocket warmers) itraconazole shows promise in clinical trials.

22. CHROMOBLASTOMYCOSIS

23. CHROMOBLASTOMYCOSIS ( Fonsecaea spp.)

24. CHROMOBLASTOMYCOSIS ( Phialophora spp.)

25. PHAEOHYPHOMYCOSIS Subcutaneous or brain abscess caused by dematiaceous fungi. Affected site : thigh , legs, feet, arms ..etc, brain (cerebral) Lesion : neuro and abcesses Etiology : (a) Dematiaceous imperfect mold fungi, mainly: Cladosporium , Exophiala , Wangiella , Cladophialphora bantiana (C. bantianum ) , Ramichloridum mackinziei , Bipolaris , Drechslera , Rhinocladiella , C. Cladosporoides , E. jeanselmei , W. dermatitidis ’

26. PHAEOHYPHOMYCOSIS (b) Neutrophic fungi : cerebral PHM as R. mackinziei , C. bantianum . Naturally in woody plant, woods, agricultural soil Laboratory diagnosis : Specimens: pus, biopsy tissue. Direct microscopic examination: KOH and smear brown septate hyphae Culture on SDA and, it’s very slow growing black or grey colonies.

27. PHAEOHYPHOMYCOSIS

28. PHAEOHYPHOMYCOSIS

29. SPOROTRICHOSIS Lesions : Lymphocutaenouse and subcutaenous granulomatous lesion-suppurate, ulcerate. The lesion are nodules or ulcers in local lymphatics Affected sites : extremities, joints. In agriculture communities Etiology Dimorphic imperfect fungus in trees, sharps, decaying vegitations . Sporothrix s chenckii . Yeast in human tissues and at 37C in culture.

30. SPOROTRICHOSIS Mold in culture and room temperatures with floweret's of conidia. Laboratory diagnosis : specimen: Biopsy tissue, ulcerative material Direct microscopy : smear ---finger – like yeast cells or cigar shaped some are oval. Culture : On SDA at room temperature to grow mold , and on blood A at 37c to grow yeast. Treatment : septrin , KI.

31. SPOROTRICHOSIS

32. SPOROTRICHOSIS

33. LOBOMYCOSIS Cutaneous -subcutaneous fungal infection Lesion : keloidal - verrucoid -nodular Site : face, ear, arms, legs Chronic-localized Etiology : Lacazia loboi = Loboa loboi Obligately parasitic fungus Does not grow in culture like SDA media or tissue culture

34. LOBOMYCOSIS Laboratory diagnosis : the specimen is biopsy tissue-direct microscopy will show chains of cells Culture of specimen will be negative Management: surgical excision of lesion

35. LOBOMYCOSIS

36. RHINOSPORIDIOSIS Clinical : Mucocutaenous fungal infection Sites : nasal, oral, (palate, epiglottis), conjunctiva Lesion : polyps, papilomas , warts-like lesion More seen in communities near swamps Etiology : Rhinosporidium seebri

37. RHINOSPORIDIOSIS Obligatory parasitic fungus Believed to be chytridiomycetes (div. mastigo ), doesn't grow on artificial media but has been grown in tissue culture Laboratory diagnosis : specimens, biopsy tissue Direct microscopy : stained section or smears KOH, will show spherules with endospores Culture on SDA will be negative Management : cryosurgical excision of lesion-relapse common

38. RHINOSPORIDIOSIS

39. RHINOSPORIDIOSIS

40. ENDEMIC MYCOSIS COCCIDIOIDOMYCOSIS . BLASTOMYCOSIS. PARACOCCIDIOIDOMYCOSIS. HISTOPLASMOSIS.

41. COCCIDIOIDOMYCOSIS Disease Coccidioides immitis causes coccidioidomycosis . Properties C. immitis is a dimorphic fungus that exists as a mold in soil and as a spherule in tissue.

42. Transmission & Epidemiology Coccidioide The fungus is endemic in arid regions of the southwestern United States and Latin America. People who live in Central and Southern California, Arizona, New Mexico, Western Texas, and Northern Mexico, a geographic region called the Lower Sonoran Life Zone, are often infected. In soil, it forms hyphae with alternating arthrospores and empty cells. Arthrospores are very light and are carried by the wind. They can be inhaled and infect the lungs.

43. Pathogenesis of Coccidioide In the lungs, arthrospores form spherules that are large, have a thick, doubly refractive wall, and are filled with endospores . Upon rupture of the wall, endospores are released and differentiate to form new spherules. The organism can spread within a person by direct extension or via the bloodstream. Granulomatous lesions can occur in virtually any organ but are found primarily in bones and the central nervous system (meningitis). Dissemination from the lungs to other organs occurs in people who have a defect in cell-mediated immunity.

44. Pathogenesis of Coccidioide Most people who are infected by C. immitis develop a cell-mediated ( delayedhypersensitivity ) immune response that restricts the growth of the organism. One way to determine whether a person has produced adequate cell-mediated immunity to the organism is to do a skin test (see below). In general, a person who has a positive skin test reaction has developed sufficient immunity to prevent disseminated disease from occurring. If, at a later time, a person's cellular immunity is suppressed by drugs or disease, disseminated disease can occur.

45. Clinical Findings of Coccidioide Infection of the lungs is often asymptomatic and is evident only by a positive skin test and the presence of antibodies. Some infected persons have an influenza like illness with fever and cough. About. 50% have changes in the lungs (infiltrates, adenopathy , or effusions) as seen on chest x-ray. 10% develop erythema nodosum (see below) or arthralgias . This syndrome is called "valley fever" or "desert rheumatism"; it tends to subside spontaneously. Disseminated disease can occur in almost any organ; the meninges , bone, and skin are important sites.

46. Clinical Findings of Coccidioide The overall incidence of dissemination in persons infected with C. immitis is 1%, although the incidence in Filipinos and African Americans is 10 times higher. Women in the third trimester of pregnancy also have a markedly increased incidence of dissemination. Erythema nodosum (EN) manifests as red, tender nodules ("desert bumps") on extensor surfaces such as the shins. It is a delayed (cell-mediated) hypersensitivity response to fungal antigens and thus is an indicator of a good prognosis.

47. Clinical Findings of Coccidioide There are no organisms in these lesions; they are not a sign of disseminated disease. EN is not specific for coccidioidomycosis ; it occurs in other granulomatous diseases, eg , histoplasmosis , tuberculosis, and leprosy . In infected persons, skin tests with fungal extracts cause at least a 5mm induration 48 hours after injection (delayed hypersensitivity reaction ). Skin tests become positive within 2-4 weeks of infection and remain so for years but are often negative in patients with disseminated disease.

48. Laboratory Diagnosis of Coccidioide In tissue specimens , spherules are seen microscopically. Cultures on Sabouraud's agar incubated at 25 °C show hyphae with arthrospores ( Caution: Cultures are highly infectious; precautions against inhaling arthrospores must be taken .) In serologic tests , IgM and IgG precipitins appear within 2-4 weeks of infection and then decline in subsequent months. Complement-fixing antibodies occur at low titer initially, but the titer rises greatly if dissemination occurs

49. COCCIDIOIDES IMMITIS SHOWING TYPICAL SINGLE-CELLED, HYALINE, RECTANGULAR TO BARREL-SHAPED, ALTERNATE ARTHROCONIDIA

50. TREATMENT & PREVENTION OF COCCIDIOIDE No treatment is needed in asymptomatic or mild primary infection . Amphotericin B ( Fungizone ) or itraconazole is used for persisting lung lesions or disseminated disease . Ketoconazole is also effective in lung disease . Fluconazole is the drug of choice for meningitis . Intrathecal amphotericin B may be required and may induce remission, but long-term results are often poor . There are no means of prevention except avoiding travel to endemic areas.

51. Tissue section showing typical endosporulating spherules of C. immitis COCCIDIOIDOMYCOSIS

52. BLASTOMYCOSIS Blastomyces dermatitidis causes blastomycosis , known as North American blastomycosis .

53. PROPERTIES OF BLASTOMYCES B. dermariridis is a dimorphic fungus that exists as a mold in soil and as a yeast in tissue. The yeast is round with a doubly refractive wall and a single broad-based bud Note that this organism forms a broad-based bud, whereas Cryptococcus neoformans is a yeast that forms a narrow-based bud.

54. TRANSMISSION & EPIDEMIOLOGY OF BLASTOMYCES This fungus is endemic primarily in eastern North America, especially in the region bordering the Ohio, Mississippi, and St. Lawrence rivers, and the Great Lakes region. Less commonly, blastomycosis has also occurred in Central and South America, Africa, and the Middle East. It grows in moist soil rich in organic material, forming hyphae with small pear-shaped conidia. Inhalation of the conidia causes human infection.

55. PATHOGENESIS & CLINICAL FINDINGS OF BLASTOMYCES Infection occurs mainly via the respiratory tract . Asymptomatic or mild cases are rarely recognized . Dissemination may result in ulcerated granulomas of skin, bone, or other sites.

56. LABORATORY DIAGNOSIS OF BLASTOMYCES In tissue biopsy specimens, thick-walled yeast cells with single broad-based buds are seen microscopically . Hyphae with small pear-shaped conidia are visible on culture. The skin test lacks specificity and has little value. Serologic tests have little value.

57. Tissue sections showing large, broad-base, unipolar budding yeast-like cells BLASTOMYCOSIS

58. TREATMENT & PREVENTION OF BLASTOMYCES Itraconazole is the drug of choice for most patients. Amphotericin B should be used to treat severe disease . Surgical excision may be helpful . There are no means of prevention.

59. PARACOCCIDIOIDOMYCOSIS Paracoccidioides brasiliensis causes paracoccidioidomycosis , also known as South American blastomycosis .

60. PROPERTIES OF PARACOCCIDIOIDES P. brasiliensis is a dimorphic fungus that exists as a mold in soil and as a yeast in tissue. The yeast is thick walled with multiple buds, in contrast to B. derrnatitidis , which has a single bud .

61. TRANSMISSION & EPIDEMIOLOGY OF PARACOCCIDIOIDES The spores are inhaled, and early lesions occur in the lungs. Asymptomatic infection is common . Alternatively oral mucous membrane lesions, lymph node enlargement, and sometimes dissemination to many organs develop.

62. LABORATORY DIAGNOSIS OF PARACOCCIDIOIDES In pus or tissues, yeast cells with multiple buds are seen microscopically. A specimen cultured for 2-4 weeks may grow typical organisms . Skin tests are rarely helpful. Serologic testing shows that when significant antibody titers (by immunodiffusion or complement fixation) are found, active disease is present.

63. TREATMENT & PREVENTION OF PARACOCCIDIOIDES The drug of choice is itraconazole taken orally for several months. There are no means of prevention.

64. MULTIPLE, NARROW BASE, BUDDING YEAST CELLS "STEERING WHEELS" OF P. BRASILIENSIS

65. PARACOCCIDIOIDOES BRASILIENSIS Multiple, narrow base, budding yeast cells "steering wheels" of P. brasiliensis

66. HISTOPLASMOSIS Histoplasma capsulatum causes histoplasmosis . H. capsulatum is a dimorphic fungus that exists as a mold in soil and as a yeast in tissue. It forms two types of asexual spores (1) Tuberculate macroconidia , with typical thick walls and fingerlike projections that are important in laboratory identification, (2 ) Microconidia , which are smaller, thin, smoothwalled spores that, if inhaled, transmit the infection.

67. TRANSMISSION & EPIDEMIOLOGY OF HISTOPLASMA This fungus occurs in many parts of the world . In the United States it is endemic in central and eastern states, especially in the Ohio and Mississippi River valleys . It grows in soil, particularly if the soil is heavily contaminated with bird droppings, especially from starlings . Although the birds are not infected, bats can be infected and can excrete the organism in their feces.

68. TRANSMISSION & EPIDEMIOLOGY OF HISTOPLASMA In areas of endemic infection, excavation of the soil during construction or exploration of bat-infested caves has resulted in a significant number of infected individuals. In several tropical African countries, histoplasmosis is caused by Histoplasrna duboisii . The clinical picture is different from that caused by H. capsulatum . A description of the differences between African histoplasmosis and that seen in the United States is beyond the scope of this book.

69. PATHOGENESIS & CLINICAL FINDINGS OF HISTOPLASMA Inhaled spores are engulfed by macrophages and develop into yeast forms. In tissues, H. capsulatum occurs as an oval budding yeast inside macrophages

70. PATHOGENESIS & CLINICAL FINDINGS OF HISTOPLASMA The yeasts survive within the phagolysosome of the macrophage by producing alkaline substances, such as bicarbonate and ammonia, that raise the pH and thereby inactivate the degradative enzymes of the phagolysosome . The organisms spread widely throughout the body; especially to the liver and spleen, but most infections remain asymptomaric , and the small grantdomatous foci heal by calcification.

71. PATHOGENESIS & CLINICAL FINDINGS OF HISTOPLASMA With intense exposure ( eg , in a chicken house or batinfested cave), pneumonia may become clinically manifest . Severe disseminated histoplasmosis develops in a small minority of infected persons, especially infants and individuals with reduced cell-mediated immunity, such as AIDS patients . In AIDS patients, ulcerated lesions on the tongue are typica ] of disseminated histoplasmosis . In immunocompetent people, EN can occur (see description of EN in Coccidioides above).

72. PATHOGENESIS & CLINICAL FINDINGS OF HISTOPLASMA EN is a sign that cell-mediated immunity is active and the organism will probably be contained . A skin test using histoplasmin (a mycelial extract) becomes positive, ie , shows at least 5 mm of induration , within 2-3 weeks after infection and remains positive for many years . However, because there are many false-positive reactions (due to cross-reactivity) and many false-negative reactions (in disseminated disease), the skin test is not useful for diagnosis.

73. PATHOGENESIS & CLINICAL FINDINGS OF HISTOPLASMA Furthermore, the skin test can stimulate an antibody response and confuse the serologic tests . The skin test is useful for epidemiologic studies, and up to 90% of individuals have positive results in areas of endemic infection.

74. LABORATORY DIAGNOSIS OF HISTOPLASMA In tissue biopsy specimens or bone marrow aspirates, oval yeast cells within macrophages are seen microscopically . Cultures on Sabouraud's agar show hyphae with tuberculate macroconidia when grown at low temperature, eg , 25°C and yeasts when grown at 37°C. Tests that detect Histoplasma antigens by radioimmunoassay and Histoplasma RNA with DNA probes are also useful.

75. LABORATORY DIAGNOSIS OF HISTOPLASMA An antibody titer of 1:32 in the CF test with yeast phase antigens is considered to be diagnostic. However, cross-reactions with other fungi, especially Blastomyces , occur. CF titers fall when the disease becomes inactive and rise in disseminated disease. The ID test detects precipitating antibodies (precipitins) by forming two bands, M and H, in an agar-gel diffusion assay. The ID test is more specific but less sensitive than the CF test.

76. PAS stain showing  Histoplasma capsulatum  yeast cells in liver specimen

77. Rough-walled macroconidia Macroconidia and microconidia HISTOPLASMA CAPSULATUM

78. INTRACELLULAR YEAST OF HISTOPLASMA

79. TREATMENT & PREVENTION OF HISTOPLASMA No therapy is needed in asymptomatic or mild primary infections. With progressive lung lesions, oral itraconazole is beneficial. In disseminated disease, arnphotericin B is the treatment of choice . In meningitis , fluconazole is often used because it penetrates the spinal fluid well.

80. TREATMENT & PREVENTION OF HISTOPLASMA Oral itraconazole is used to treat pulmonary or disseminated disease, as well as for chronic suppression in patients with AIDS. There are no means of prevention except avoiding exposure in areas of endemic infection.

81. SUMMARY Agent infection Dissemination Drug of choice Blastomyces dermatitidis Blastomycosis Skin and bone Later nervous system and visceral organs Amphotericin B itraconazole Coccidioides immitis Coccidioidomycosis Skin, bones, joints, subcutaneous tissues, and visceral organs Amphotericin B Paracoccidioidoes brasiliensis Paracoccidioidomycosis Oro-nasal mucosa latter spleen, liver, intestine and skin Amphotericin B + sulfas or azoles Histoplasma capsulatum Histoplasmosis Acute pneumonia (cave disease) Chronic pneumonia (smoker) Disseminated ( immunocompromised ) Primary cutaneous (lab accidents) Amphotericin B

82. OPPORTUNISTIC MYCOSES Opportunistic mycoses are fungal infections that do not normally cause disease in healthy people. Do cause disease in people with weakened immune defenses ( immunocompromised people). Weakened immune function may occur due to inherited immunodeficiency diseases, drugs that suppress the immune system (cancer chemotherapy, corticosteroids, drugs to prevent organ transplant rejection), radiation therapy, infections (e.g., HIV), cancer, diabetes, advanced age and malnutrition.

83. CLASSIFICATION OF OPPORTUNISTIC MYCOSE Candidiasis . Aspergillosis . Cryptococcosis . Mucormycosis .

84. CANDIDIASIS C. albicans is a member of the indigenous microbial flora of humans.  Found in the gastrointestinal tract, upper respiratory tract, buccal cavity, and vaginal tract . Growth is normally suppressed by other microorganisms found in these areas . Alterations of gastrointestinal flora by broad spectrum antibiotics or mucosal injury can lead to gastrointestinal tract invasion.

85. CANDIDIASIS Skin and mucus membranes are normally an effective barrier but damage by introduction of catheters or intravascular devices can permit Candida to enter the bloodstream. In healthy individuals candida causes Vaginitis and Diaper rash. Severe disseminated candidiasis most commonly occurs in neutropenic patients due to leukemia, chemotherapy etc. and leads to DIC or shock.

86. PATHOGENESIS OF CANDIDIASIS A single strain of candida can be successful as commensal & pathogen. Candida shift between different phenotypes called “ phenotypic switching “. Phenotypic switching involves co- ordinated regulation of phase specific genes. These variants exhibit altered colony morphology, cell shape, Antigenicity & virulence.

87. PATHOGENESIS OF CANDIDIASIS Candida produce large number of functionally distinct Adhesins that contribute virulence. Adhesins include- Integrin like protein that binds to fibronectin , laminin . A protein that binds to epithelial cells Several agglutinins that bind to endothelial cells / fibronectin .

88. PATHOGENESIS OF CANDIDIASIS Candida produce enzymes like- Asprtyl proteinases - Tissue invasion by degrading extracellular matrix. Catalases - Resist oxidative killing by phagocytic cells. C. albicans grow as biofilms ( microbial communities 0f yeast +filamentous form ), specially on prosthetic materials.

89. PATHOGENESIS OF CANDIDIASIS Neutrophis , macropgages & T H 17 cells are important for protection against candida infection. Neutrophil & macrophages phagocytose candida and oxidative killing by phagocytic first line Host defence . Increased risk of canida infection in Neutropenic patients or patients with NADPH Oxidase / Myeloperoxidase defficiency . Filamentous form can escape from phagocytic damage.

90. PATHOGENESIS OF CANDIDIASIS Yeast cell β 1-3 glucan Dectin on dendritic cells Induce production of IL-6, IL-23 TH 17 response Recruitment of neutrophil & monocytes .

91. CLINICAL FINDINGS OF CANIDIDIASIS

92. OPPORTUNISTIC INFECTION BY CANDIDA ALBICANS IN AN AIDS PATIENT

93. LAB DIAGNOSIS OF CANDIDA In tissue section C. albicans appearas as yeast, PSEUDOHYPHAE . Pseudohyphae are chain of budding yeast cells joined end to end at constrictions. All forms may be present togather and seen in H & E stain. Special fungal stain like Gomori Methamine Silver, PAS can better visualize them.

94. MORPHOGENESIS Figure 2 . Morphogenic forms of Candida albicans Figure 1 . Morphogenesis. Morphogenesis in C. albicans is a pivotal virulence factor that allows rapid multiplication and subsequent dissemination in host tissue.

95. FIGURE 1. SKIN EQUIVALENT BEFORE INFECTION FIGURE 2. INFECTION WITH PATHOGENIC CLINICAL ISOLATE OF C. ALBICANS . AFTER 48 H THE YEAST PENETRATES THE SKIN EQUIVALENT AND DESTROYS THE TISSUE FIGURE 3. INFECTION WITH NON-PATHOGENIC C. ALBICANS . THIS STRAIN IS NOT ABLE TO PENETRATE INTO THE TISSUE AND THUS BEHAVES AS AVIRULENT AS SHOWN IN THE MOUSE MODEL OF SYSTEMIC INFECTION. VIRULENCE ASSAY OF DIFFERENT C. ALBICANS STRAINS USING THE SKIN EQUIVALENT

96. ASPERGILLOSIS Aspergillus fumigatus most common pathogenic species causes diseases in human. Portal of entry – Inhalation of conidia. Major Risk factors Neutropenia . Use of corticosteroids.

97. PATHOGENESIS OF ASPERGILLOIS Alveolar macrphages recognize aspergillus through TLR-2 & Lectin Dectin - 1 ( which recognizes β 1, 3 glucan of conidia ). Activation of phagocytes to ingest & kill conidia. In immunosuppressed patients conidia can germinate into hyphae , which invades tissue.

98. PATHOGENESIS OF ASPERGILLOIS TLR recognizes products of hyphae & release pro inflammatory Cytokines like IL- β , TNF- α & Chemokines Neutrophils come into action Oxidative damage of hyphae Invasive aspergillosis highly associated with Neutropenia & impaired neutrophil defenses.

99. PATHOGENESIS OF ASPERGILLOIS Virulence Factors : Adhesins . Antioxidants( Melanin, Catalase , SOD ). Toxins ( Aflatoxin -> Ca Liver ).

100. CLINICAL FINDINGS OF ASPERGILLOSIS Sinusitis, Aspergillus asthma. Colonizing Aspergillosis ( Aspergilloma ) - growth of fungus in pre existing pulmonary cavity -> Fungal ball -> recurrent haemoptysis . Invasive Aspergillosis - Immunosuppressed host, widespread hematogenous spread involves heart valves, brain. Pulmonary invasive aspergillosis show necrotizing pneumonia (Target lesion ).

101. LAB DIGNOSIS OF ASPERGILLOSIS Form fruiting bodies & hyaline septate hyphae , branching at acute angle (40 degree ).

102. CRYPTOCOCCOSIS Human disease - C. neoformans C. gattii . Risk Factors : AIDS Leukemia. Lymphoma. Immunosuppressed transplant individuals. Presnt in soil & bird droppings and Mode of transmission is Inhalation . C. gattii causes infection in otherwise normal individual.

103. PATHOGENESIS OF CRYPTOCOCCOSIS Virulence Factors : Polysaccharide capsule - prevent phagocytosis (Phenotypic switching ). Melanin Anti oxidant property. Cell wall integrity. Counteract effects of antifungal agents. Decreased phagocytosis . Enzymes – Phenol Oxidase , cleaves fibronectin & other basement membrane protein ,aids tissue invasion.

104. CLINICAL FINNDINGS OF CRYPTOCOCCOSIS Involves meninges , cortical grey matter and basal nuclei. In immunocompromised individuals gelatinous masses of fungi grow in meninges . Skin involvement is second common. Bone incolvement may also occur.

105. LAB DIAGNOSIS OF CRYPTOCOCCOSIS In CSF :Capsule negatively stained in indian ink preparation. In tissue specimen : 5 – 10 micrometer cryptococcal yeast characterised by intense red polysccharide capsule in mucicarmine & PAS stain.

106. MUCORMYCOSIS Mucormycotina are widely distributed in nature. No harm to immunocompetent individulas . They infect immunosuppressed people, causing mucormycosis . Causative agents Mucor Rhizopus Cunninghamella . Mode of transmission : Inhalation

107. PATHOGENESIS OF MUCORMYCOSIS Inhaled spore causes infection in the sinuses & lungs. Macrophages provide initial defence by phagocytosis & nonoxidative killing of sporangiospores . Hyphal component of mucormycotina recognized by TLR- 2  release of proinflammatory cytokines (IL-6 , TNF – α ) & Chemokines neutrophils  damage to hyphal wall.

108. PATHOGENESIS OF MUCORMYCOSIS Iron promotes growth of mucormycotina . Increased possibility of infection seen in diabetics due to increased free Iron ( ketoacidosis , glycosylation induced poor affinity for iron )

109. CLINICAL FINDINGS OF MUCORMYCOSIS Rhino cerebral mucormycosis : Local tissue necrosis , invade arterial walls & penetrates the periorbital tissue & cranial vault  Meningoencephalitis with or without cerebral infarction. Lung involvement : Hemorrhagic pneumonia.

110. LAB DIAGNOSIS OF MUCORMYCOSIS In Tissue specimen : Non septate hyphae with branching at right angle (distinct from aspergillus ) readily demonstrated in H & E stained section. Culture : In SDA @ 37 degree C. Dense Hairy Colony.